This invention is generally directed to photoconductive imaging members, and more specifically to imaging members with polycarbonate binders. The present invention in one embodiment is directed to layered imaging members comprised of charge transport layers with charge transport molecules dispersed in polycarbonate binder, which novel polycarbonates contain telechelic polysiloxane macromers. In a specific embodiment, the present invention relates to layered imaging members comprised of a photogenerating layer and a hole transport layer wherein the transport molecules thereof are dispersed in a polycarbonate resinous binder, which polycarbonates have incorporated therein polysiloxane telomers during, for example, a polyesterification reaction. Further, in another embodiment of the present invention the imaging member is comprised of a supporting substrate, a photogenerating layer, and in contact therewith a charge, especially a hole transport layer comprised of hole transport molecules dispersed in the aforementioned polycarbonate resinous binder. The charge transport layer can be located as the top layer of the imaging member, or alternatively it may be situated between a supporting substrate and the photogenerating layer. The aforementioned polycarbonate binders can possess a number of advantages including, for example, resistance to abrasion, increased tensile toughness of up to fifty fold times more relative to polycarbonate Z, from about 2 Joules/cm.sup.3 to about 100 Joules/cm.sup.3, increased elongation to break of five to ten times more relative to polycarbonate Z, the solubility thereof in a number of solvents such as aromatic solvents including toluene, tetrahydrofuran, xylene, and benzene, and aliphatic solvents such as halogenated hydrocarbons thus permitting, for example, and improved coatability thereof with organic charge transport components utilizing various known processes such as spray, dip, and draw-down coating. Another advantage associated with many of the imaging members of the present invention resides in the ability to modify the substituents, or side groups present on the polycarbonates thereby providing, for example, substantial latitude in improving the mechanical and surface properties of the charge transport layers including, for example, environmental stability, abrasion resistence, elimination of a protective top coating, and/or excellent paper stripping characteristics for the imaging member.
The tensile toughness represents the area of a stress strain curve when a sample of the material is strained to its breaking point, this phrase being well known in the art, and moreover there can be selected a known tensile test for films and coatings of the polycarbonate binders, which tests are capable of enabling the calculation of the Young's modulus, tensile strength, yield strength, percent elongation, and tensile toughness.
The novel polycarbonates binders illustrated herein may also be selected in an embodiment of the present invention as a resin binder for the charge generating layer, particularily since it is believed that such a binder may enable improved photogenerating pigment dispersion stability, and increased photosensitivity for the resulting imaging member.
The imaging members of the present can be selected for a number of imaging and printing processes including electrophotographic imaging and printing processes for an extended number of imaging cycles, exceeding 200,000, for example, while substantially avoiding or minimizing abrasion thereof. Also, the imaging members of the present invention can be selected for a number of color imaging and printing processes.
The formation and development of electrostatic latent images on the imaging surfaces of photoconductive materials by electrostatic means is well known. Numerous different photoconductive members for use in xerography are known such as selenium, alloys of selenium, layered imaging members comprised of aryl amine charge transport layers, reference U.S. Pat. No. 4,265,990, and imaging members with charge transport layers comprised of polysilylenes, reference U.S. Pat. No. 4,618,551. The disclosures of the aforementioned patents are totally incorporated herein by reference. With the aforementioned imaging members, especially those of the '990 patent, there are selected aryl amine charge transport layers, which aryl amines are soluble in halogenated hydrocarbons such as methylene chloride. Further, the polycarbonates of the present invention can also be selected as resinous binders for imaging members with electron transport layers, reference U.S. Pat. No. 4,474,865, the disclosure of which is totally incorporated herein by reference.
In U.S. Pat. No. 4,869,988 and U.S. Pat. No. 4,946,754, the disclosures of which are totally incorporated herein by reference, there are described layered photoconductive imaging members with transport layers incorporating, for example, biarylyl diarylamines, N,N-bis(biarylyl)anilines, and tris(biarylyl)amines as charge transport compounds. In the above-mentioned patents, there are disclosed improved layered photoconductive imaging members comprised of a supporting substrate, a photogenerating layer optionally dispersed in an inactive resinous binder, and in contact therewith a charge transport layer comprised of the above-mentioned charge transport compounds, or mixtures thereof dispersed in resinous binders.
Examples of specific hole transporting components disclosed in U.S. Pat. No. 4,869,988 include N,N-bis(4-biphenylyl)-3,5-dimethoxyaniline (Ia); N,N-bis(4-biphenylyl)-3,5-dimethylaniline (Ib); N,N-bis(4-methyl-4'-biphenylyl)-3-methoxyaniline (Ic); N,N-bis(4-methyl-4'-biphenylyl)-3-chloroaniline (Id); N,N-bis(4-methyl-4'-biphenylyl)-4-ethylaniline (Ie); N,N-bis(4-chloro-4'-biphenylyl)-3-methylaniline (If); N,N-bis(4-bromo-4'-biphenylyl)-3,5-dimethoxy aniline (Ig); 4-biphenylyl bis(4-ethoxycarbonyl-4'-biphenylyl)amine (IIa); 4-biphenylyl bis(4-acetoxymethyl-4'-biphenylyl)amine (IIb); 3-biphenylyl bis(4-methyl-4'-biphenylyl)amine (IIc); 4-ethoxycarbonyl-4'-biphenylyl bis(4-methyl-4'-biphenylyl)amine (IId); and the like.
Examples of specific hole transporting compounds disclosed in U.S. Pat. No. 4,946,754 include bis(p-tolyl)-4-biphenylylamine (IIa); bis(p-chlorophenyl)-4-biphenylylamine (IIb); N-phenyl-N-(4-biphenylyl)-p-toluidine (IIc); N-(4-biphenylyl)-N-(p-chlorophenyl)-p-toluidine (IId); N-phenyl-N-(4-biphenylyl)-p-anisidine (IIe); bis(m-anisyl)-4-biphenylylamine (IIIa); bis(m-tolyl)-4-biphenylylamine (IIIb); bis(m-chlorophenyl)-4-biphenylylamine (IIIc); N-phenyl-N-(4-biphenylyl)-m-toluidine (IIId); N-phenyl-N-(4-bromo-4'-biphenylyl)-m-toluidine (IVa); diphenyl-4-methyl-4'-biphenylylamine (IVb); N-phenyl-N-(4-ethoxycarbonyl-4'-biphenylyl)-m-toluidine (IVc); N-phenyl-N-(4-methoxy-4'-biphenylyl)-m-toluidine (IVd); N-(m-anisyl)-N-(4-biphenylyl)-p-toluidine (IVe); bis(m-anisyl)-3-biphenylylamine (Va); N-phenyl-N-(4-methyl-3'-biphenylyl)-p-toluidine (Vb); N-phenyl-N-(4-methyl-3'-biphenylyl)-m-anisidine (Vc); bis(m-anisyl)-3-biphenylylamine (Vd); bis(p-tolyl)-4-methyl-3'-biphenylylamine (Ve); N-p-tolyl-N-(4-methoxy-3'-biphenylyl)-m-chloroaniline (Vf), and the like. The aforementioned charge, especially hole transport components, can be selected for the imaging members of the present invention in embodiments thereof.
It is also indicated in the aforementioned patents that there may be selected as resin binders for the charge transport molecules those components as illustrated in U.S. Pat. No. 3,121,006 including polycarbonates, polyesters, epoxy resins, polyvinylcarbazole; and also wherein for the preparation of the charge transport layer with a polycarbonate there is selected methylene chloride as a solvent.
There is also mentioned as prior art U.S. Pat. Nos. 4,657,993, the disclosure of which is totally incorporated herein by reference, directed to polyphosphazene homopolymers and copolymers of the formula as recited, for example, in the Abstract of the Disclosure, which components may be selected as photoconductive materials and for other uses, see column 1, and continuing on to column 2; and as background interest directed to processes for the preparation of phosphonitrilic polymer mixtures, reference the Abstract of the Disclosure; 3,515,688 related to phosphonitrile elastomers, reference for example the Abstract of the Disclosure; 3,702,833 directed to curable fluorophosphazene polymers, see for example column 1; and 3,856,712 directed to polyphosphazene copolymers which are elastomers. The disclosures of each of the aforementioned patents are totally incorporated herein by reference.
While imaging members with various charge transporting substances, especially hole transports, including the aryl amines disclosed in the prior art, are suitable for their intended purposes, there continues to be a need for improved imaging members, particularly layered members, with abrasion resistant resin binders. Another need resides in the provision of layered imaging members that are compatible with liquid developer compositions. Further, there continues to be a need for layered imaging members wherein the layers are sufficiently adhered to one another to allow the continuous use of such members in repetitive imaging systems. Also, there continues to be a need for improved layered imaging members comprised of hole transport layers wherein the problems of transport molecule crystallization, bleeding and leaching are avoided or minimized. Furthermore, there is a need for imaging members with charge transport compounds or polymers dispersed in certain polycarbonate resin binders that are soluble in nontoxic solvents, and wherein the resulting imaging members are inert to the users thereof. A further need resides in the provision of photoconductive imaging members with desirable mechanical characteristics.